1. Field of the Invention
The present invention relates generally to leveling systems and particularly leveling systems which rely on hydrostatic pressure and the fact that fluids at equal pressures and in fluid flow communication will equalize. More particularly, the present invention relates to a method of using a hydrostatic leveling system to precisely level large, unwieldy objects, such as reciprocating gas compressors used in the petrochemical industry and the like.
2. Description of Prior Art
Related art may be found in U.S. Class 33, subclasses 367 and 378, Class 73, subclasses 722 and 728, among others. Of particular relevance is my prior patent, U.S. Pat. No. 4,384,410, the teachings of which are expressly incorporated by reference herein.
In my earlier patent, a hydrostatic leveling device was presented that used the self-leveling principle. This principle was utilized in a U-tube manometer where, in the absence of some applied force or pressure, the liquid level in the two arms of the U-tube will be at the same level. Even if the two arms of the U-tube were separated by a substantial distance, the liquid level would be the same in each tube.
The extended U-tube arrangement mentioned above and discussed in great detail in my earlier patent was utilized as a leveling device on limited occasions but it was mainly used for vertical measurements. The original function of the level was to measure the difference between one vertical plane and another vertical plane. This difference was measured on a pair of interconnected, spaced apart indicating heads. The vertical difference between these respective planes was measured directly by the movement of the floats attached to each indicating head. However, these measurements suffered from several problems decreasing their accuracy. For example, as the floats move off of zero or a neutral position there is interference caused by the hysteresis and friction of the mechanical indicator. Also, there is friction of movement of mercury on the sides of the mercury container, the float, and the connecting hose. Also on the original level, measurements were limited to less than one quarter inch of vertical movement.
The manufacturers of mechanical indicators as well as electrical indicator and electrical transducers or L.V.D.T. (Linear Variable Differential Transformer) admit in their claims of accuracy for their equipment, that the farther you move off of zero position or a null position, the more inaccurate the measurement is. In other words, their equipment will measure levelness far move accurately than it will measure vertical differences.
Another problem in many industries, especially the petrochemical industry, where large reciprocating gas compressors are used, is the lack of appropriate surfaces to set the indicating heads on. These motors are often thirty or forty feet long and generate from one to five thousand horsepower. When you add the power pistons as well as the compressor pistons to the movement of the main crankshaft you have dynamic movement in several different directions at the same time that causes a great deal of vibration.
In fact, in almost all cases the only precision machined surface that is exposed is the bottom of the engine frame. While the engine frame bottom is often exposed, there is generally less than one inch of space between the bottom of the frame and the foundation that the compressor sets upon.
Due to the small amount of room available to the operator to have access to a machined surface (the bottom of the engine) as well as the extreme vibration caused by the operation of the engine, it is very difficult to get a precision profile of the bottom of the engine.